Can't get location with Mapsforge

Question

I'm trying to get the latitude and longitude with Mapsforge 0.6.1, but an error appears. I'm using Android Studio.

Logcat:

E/AndroidRuntime: FATAL EXCEPTION: main
   Process: com.example.luis.safe, PID: 27378
   java.lang.RuntimeException: Unable to create service com.example.luis.safe.Tracker: java.lang.NullPointerException: Attempt to invoke virtual method 'double org.mapsforge.core.model.LatLong.getLatitude()' on a null object reference
       at android.app.ActivityThread.handleCreateService(ActivityThread.java:2905)
       at android.app.ActivityThread.access$1900(ActivityThread.java:157)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1439)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:148)
       at android.app.ActivityThread.main(ActivityThread.java:5530)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:732)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)
    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'double org.mapsforge.core.model.LatLong.getLatitude()' on a null object reference
       at com.example.luis.safe.Tracker.onCreate(Tracker.java:57)
       at android.app.ActivityThread.handleCreateService(ActivityThread.java:2895)
       at android.app.ActivityThread.access$1900(ActivityThread.java:157) 
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1439) 
       at android.os.Handler.dispatchMessage(Handler.java:102) 
       at android.os.Looper.loop(Looper.java:148) 
       at android.app.ActivityThread.main(ActivityThread.java:5530) 
       at java.lang.reflect.Method.invoke(Native Method) 
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:732) 
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622) 

This is my code. In the onCreate method, I call getLatitude, and the error appears.

import android.Manifest;
import android.app.Service;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.os.IBinder;
import android.support.v4.app.ActivityCompat;
import android.util.Log;

import com.google.android.gms.common.api.GoogleApiClient;

import org.mapsforge.core.model.LatLong;
import org.mapsforge.map.model.MapViewPosition;
import org.mapsforge.core.model.Point;
import org.mapsforge.core.model.BoundingBox;

public class Tracker extends Service implements LocationListener{
    public Tracker() {
    }

    // flag for GPS status
    boolean isGPSEnabled = false;

    // flag for network status
    boolean isNetworkEnabled = false;

    boolean canGetLocation = false;

    private static final String TAG = Tracker.class.getSimpleName();

    Location location;
    double latitude = 0.0;
    double longitude = 0.0;

    private LatLong latLong;

    // The minimum distance to change Updates in meters
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 5; // 5     meters

    // The minimum time between updates in milliseconds
    private static final long MIN_TIME_BW_UPDATES = 1000 * 5 * 1; // 5     segundos, 1000 * 60 * 1 ---> 1 minuto

    // Declaring a Location Manager
    protected LocationManager locationManager;

    @Override
    public void onCreate() {
        super.onCreate();

        latitude = latLong.getLatitude();
        longitude = latLong.getLongitude();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException("Not yet implemented");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        //myTask.execute();
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderDisabled(String arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onLocationChanged(Location arg0) {
        System.out.println(latitude + "" + longitude);

    }

    @Override
    public void onDestroy() {
        super.onDestroy();

    }
}

Answer 1

As the log is saying: latLong is null. You cannot getLatitude() or getLongitude() before having initialized latLong. Initialize latLong in onLocationChanged(Location arg0). And check out this code in order to understand what else you should be doing.